META-ANALYSIS Total, dietary, and supplemental calcium intake and mortality from all-causes, cardiovascular disease, and cancer: A meta-analysis of observational studies Z. Asemi a, 1 , P. Saneei b,c,d, 1 , S.-S. Sabihi b,c , A. Feizi e , A. Esmaillzadeh b,c, * , 1 a Research Center for Biochemistry and Nutrition in Metabolic Diseases, Kashan University of Medical Sciences, Kashan, Isfahan, Iran b Food Security Research Center, Isfahan University of Medical Sciences, Isfahan, Iran c Department of Community Nutrition, School of Nutrition and Food Science, Isfahan University of Medical Sciences, Isfahan, Iran d Students’ Research Committee, Isfahan University of Medical Sciences, Isfahan, Iran e Department of Epidemiology and Biostatistics, School of Public Health, Isfahan University of Medical Sciences, Isfahan, Iran Received 18 September 2014; received in revised form 14 March 2015; accepted 16 March 2015 Available online --- KEYWORDS Calcium; Mortality; Meta-analysis; Diet Abstract Aims: This systematic review and meta-analysis of observational studies was conduct- ed to summarize the evidence on the association between calcium intake and mortality. Methods and results: PubMed, Institute for Scientiﬁc Information (ISI) (Web of Science), SCOPUS, SciRUS, Google Scholar, and Excerpta Medica dataBASE (EMBASE) were searched to identify related articles published through May 2014. We found 22 articles that assessed the association between total, dietary, and supplementary intake with mortality from all-causes, cardiovascular disease (CVD), and cancer. Findings from this meta-analysis revealed no signiﬁcant association between total and dietary calcium intake and mortality from all-causes, CVD, and cancer. Sub- group analysis by the duration of follow-up revealed a signiﬁcant positive association between total calcium intake and CVD mortality for cohort studies with a mean follow-up duration of >10 years (relative risk (RR): 1.35; 95% conﬁdence interval (CI): 1.09e1.68). A signiﬁcant inverse association was seen between dietary calcium intake and all-cause (RR: 0.84; 95% CI: 0.70e1.00) and CVD mortality (RR: 0.88; 95% CI: 0.78e0.99) for studies with a mean follow-up duration of 10 years. Although supplemental calcium intake was not associated with CVD (RR: 0.95; 95% CI: 0.82e1.10) and cancer mortality (RR: 1.22; 95% CI: 0.81e1.84), it was inversely associated with the risk of all-cause mortality (RR: 0.91; 95% CI: 0.88e0.94). Conclusions: We found a signiﬁcant relationship between the total calcium intake and an increased risk of CVD mortality for studies with a long follow-up time and a signiﬁcant protective association between dietary calcium intake and all-cause and CVD mortality for studies with a mean follow-up of 10 years. Supplemental calcium intake was associated with a decreased risk of all-cause mortality. ª 2015 Elsevier B.V. All rights reserved. Introduction Findings from epidemiological studies have indicated an inverse association between dietary calcium intake and * Corresponding author. Department of Community Nutrition, School of Nutrition and Food Science, Isfahan University of Medical Sciences, Isfahan, PO Box 81745-151, Iran. Tel.: þ98 311 7922720; fax: þ98 311 6682509. E-mail address: Esmaillzadeh@hlth.mui.ac.ir (A. Esmaillzadeh). 1 Co-ﬁrst author. Please cite this article in press as: Asemi Z, et al., Total, dietary, and supplemental calcium intake and mortality from all-causes, cardiovascular disease, and cancer: A meta-analysis of observational studies, Nutrition, Metabolism & Cardiovascular Diseases (2015), http://dx.doi.org/10.1016/j.numecd.2015.03.008 http://dx.doi.org/10.1016/j.numecd.2015.03.008 0939-4753/ª 2015 Elsevier B.V. All rights reserved. Nutrition, Metabolism & Cardiovascular Diseases (2015) xx,1e 12 Available online at www.sciencedirect.com Nutrition, Metabolism & Cardiovascular Diseases journal homepage: www.elsevier.com/locate/nmcd